High CPU and memory usage while editing queries

Start by reproducing the issue with the listed VS Code and CodeQL extension versions, following the steps for editing the generated example.ql while monitoring the OpenJDK Platform binary process. Investigate the related issue #594 and determine what work continues after edits; done means the cause is identified and CPU and memory usage during ordinary editing are improved.

Describe the bug
The performance when just editing queries, not even compiling or running them yet, is not very good. I get high CPU usage (80% for a notebook with 6 cores / 12 processors, running at > 3 GHz), and high memory usage (> 4 GB just by the OpenJDK process of the extension). And this high CPU and memory usage can sometimes even last a few seconds after you made the last edit in the query source code.

It does not even have to be a complex query or query suite, I even get this for the sample "Hello world".
Example:

https://github.com/user-attachments/assets/d5b5cf0c-b6a4-489e-9bfa-18bf3c167a39

Disabling Microsoft Defender Real-time protection did not seem to make a difference.

I know this comparison might not be fair since CodeQL is quite different from lots of other programming languages, but I haven't seen such performance problems with other programming languages or IDEs yet. For example in a Java project in IntelliJ memory usage is about 2 GB, and writing code might trigger some CPU usage spikes up to 40%, but only for a very short time.

Maybe related to #594?

Version
(this is not a new problem, I think I have seen this for a few months already)

VS Code:

Version: 1.106.3 (user setup)
Commit: bf9252a2fb45be6893dd8870c0bf37e2e1766d61
Date: 2025-11-25T22:28:18.024Z
Electron: 37.7.0
ElectronBuildId: 12781156
Chromium: 138.0.7204.251
Node.js: 22.20.0
V8: 13.8.258.32-electron.0
OS: Windows_NT x64 10.0.26100

CodeQL extension:

CodeQL extension version: 1.17.6 
CodeQL CLI version: 2.23.6 
Platform: win32 x64

To reproduce

1. Open a new empty folder in VS Code
2. Open the Windows Task Manager next to VS Code
3. Use the command "CodeQL: Create Query"
4. Select "Java" as language
5. Edit the generated example.ql, write some arbitrary CodeQL code at fairly decent speed
   ❌ Issue: The extension (more specifically the corresponding "OpenJDK Platform binary" process) shows high CPU and memory usage

Expected behavior
Performance while editing queries should be better

Additional context
Not really sure, and I am really wondering why others have not reported this before.
I don't think there is anything special about my setup, I have no custom CodeQL settings (other than controllerRepo), and as shown above this even occurs for the "Hello world" sample.